Test lead probe with retractable insulative sleeve

TECHNICAL FIELD

This invention relates generally to test instrument lead probes, and more specifically one or more embodiments relate to test probes having adjustable length probe tips.

BACKGROUND OF THE INVENTION

Test instruments, such as multimeters, voltage meters, oscilloscopes and the like, are used to measure electrical parameters in various electrical devices. <figref idrefs="DRAWINGS">FIG. 1</figref> illustrates an exemplary test instrument <b>100</b>. The test instrument <b>100</b> has a test probe <b>102</b> that is coupled to an input/output <b>104</b> of the test instrument <b>100</b>. The test probe <b>102</b> has a test lead <b>106</b> having a first end <b>108</b> that is coupled to the input/output <b>104</b> of the test instrument <b>100</b> and a second end <b>110</b> that is coupled to a probe body <b>112</b>. The probe body <b>112</b> includes a tip <b>114</b>, which is coupled to a test point (not shown) of a device (not shown) to be measured or tested. As will be clear to a person having ordinary skill in the art, a second test probe (not shown), such as a ground connector, may be coupled to input/output <b>105</b>.

In general, different length test probe tips are used in various test applications. In the past, to accommodate the need for different length probe tips, various test probe assemblies having different probe tip lengths were used with test instruments. For instance, a user may have two sets of test probes, one probe set with long length probe tips and another set with short probe tips. Another method for accommodating for the need of different length probes has been to use probe tips that are removable from the probe holder or body. Thus, rather than replacing the entire probe assembly, only the probe tip needs to be replaced. However, both of these solutions require a user to have to manage two sets of test probes, either the entire test probe assembly or test probe tips. Often test points are located in an obstructed location and having multiple test probes or probe tips can result in problems for the user when switching out the different probes. For instance, the user may have difficulty carrying the extra probes or the equipment may put the user in an awkward position so that it is a challenge to change out the probes. Additionally, by having separate test probes, the user may misplace, drop, or lose the probes so that the appropriate probe or probe tip is not available when needed.

More recently, however, test probes have been designed with probe tips that are slideable within the probe holder or body. Thus, rather than replacing the entire probe assembly when a different length probe tip is required, the probe tip slides in and out of the probe body and is locked into position at a desired length. For instance, when a longer probe tip is required, a locking mechanism that holds the probe tip within the probe body may be released so that the probe tip is free to move within the probe body. A user may then slide the probe tip so that a greater portion of the probe tip is exposed from the probe body and lock the probe tip into position. Therefore, rather than replacing the probe assembly or the probe tip, a single probe tip may act as a varying length probe tip. When a long probe length is needed, the probe tip slides out of the probe body so that more of the probe tip extends from the probe body. When a short probe length is needed, some of the exposed probe tip slides back into the probe body so that less of the probe tip extends from the probe body. Consequently, a single probe tip provides versatility and a user does not need to carry around probes having varying lengths.

Recently safety standards have been developed that limit the length of the exposed probe tip. In particular, the International Electrotechnical Commission (IEC), under the guidance of Technical Committee (TC66), generated a safety standard for Test and Measurement Equipment related to test probes referenced as IEC-61010-031. This standard specifies requirements for test probe tips for various test applications. For instance, the safety standard specifies the length of the exposed metal tip of the probe used in industrial applications, referred to as category III (CAT III) and category IV (CAT IV) installation, must be less than 4 mm in length. The probe tip for low energy applications, such as used in household applications or category II (CAT II) installations, must be less than 18 mm in length. Having a probe tip with exposed metal 18 mm in length is important because this allows users to easily insert the probe tip into a standard wall socket for quick and accurate measurement, which is not possible with a 4 mm probe tip. For industrial applications (CAT III and CAT IV) where high energy exists, a reduced probe tip of 4 mm is important to help reduce risk of arcs and arc flash hazards, which is not an issue in CAT II environments.

Therefore, when using a slideable probe tip described above, a user will not know whether the exposed length of the probe tip is within the specified length to meet the safety standard unless a measurement is made on the exposed length of the probe tip each time the probe tip length is adjusted. This requires a user to carry a measurement tool and results in a time consuming second step. Although a user may expose a portion of the probe tip that is significantly less than required by the safety standards discussed above and not have to make a measurement, most applications require the entire amount allowed under the safety standard. For instance, in household application, a user will need a probe tip to be very close to the 18 mm maximum length because it will allow the user to insert the probe tip into standard wall sockets.

There is, therefore, a need for a test probe having an adjustable length probe tip that indexes to predetermined lengths. Additionally, there is a need for an adjustable probe tip that communicates to a user the length of the exposed probe tip.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed toward test probes used with test and measurement equipment, and more particularly, one or more embodiments relate to test probes with probe tips having lengths that are indexable to at least two positions. In one aspect of the invention a test probe includes a conductive member having a main section and a first end, the first end being defined by an electrically conductive tip. The test probe further includes an insulative member surrounding a portion of the main section of the conductive member. The test probe further includes an insulative sleeve positioned between the insulative member and the conductive member. The insulative sleeve may be mechanically coupled to the insulative member to cause axial movement of the insulative sleeve relative to the conductive member.

In another aspect of the invention a test probe includes an insulative member having an opening at a first end. An inner surface of the insulative member includes at least one protrusion. The test probe further includes an insulative sleeve positioned within the opening of the insulative member. The insulative sleeve has at least one slot aligned with a respective one of the at least one protrusion. The test probe further includes a conductive member extending from a first end of the insulative sleeve. The conductive member has an electrically conductive tip defining a first end.

Another aspect of the invention includes a method for adjusting a length of a probe tip exposed from an insulative component. The method includes providing a first length of the insulative sleeve extending from the test probe, and altering the length of the insulative sleeve extending from the test probe from the first length to a second length by physical characteristics in the test probe. The second length being a specific distance from the first length.

BRIEF DESCRIPTION OF THE DRAWINGS

<figref idrefs="DRAWINGS">FIG. 1</figref> is a schematic drawing of a test instrument in accordance with prior art.

<figref idrefs="DRAWINGS">FIG. 2A</figref> is a schematic drawing of a test probe according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 2B</figref> is a schematic drawing of a test probe according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 3A</figref> is a cross sectional schematic drawing of a test probe according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 3B</figref> is a cross sectional schematic drawing of a test probe according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 4A</figref> is an isometric schematic drawing of an insulative sleeve according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 4B</figref> is an isometric schematic drawing of an insulative sleeve according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 5A</figref> is an isometric schematic drawing of the top portion of the probe body according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 5B</figref> is a cross sectional schematic drawing of the top portion of the probe body according to one embodiment of the invention.

<figref idrefs="DRAWINGS">FIG. 5C</figref> is an schematic drawing of the top portion of the probe body according to one embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention are directed toward test probes used with test and measurement equipment, and more particularly, one or more embodiments relate to test probes with probe tips having lengths that are indexable to at least two positions. In some embodiments, a test probe includes a retractable insulative sleeve that indexes to a plurality of positions. The insulative sleeve may be indexed using a mechanical system, an optical system, or any combination thereof. Certain details are set forth below to provide a sufficient understanding of the embodiments of the invention. However, it will be clear to one skilled in the art that various embodiments of the invention may be practiced without these particular details.

<figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref> are schematic drawings of a test probe <b>200</b> according to one embodiment of the invention. The test probe <b>200</b> in <figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref> includes a probe tip <b>202</b> and a probe body <b>204</b>. The probe tip <b>202</b> is made from an electrically conductive material, and is configured to be placed in electrical communication with a test point (not shown) of an electrical device (not shown). The probe body <b>204</b> is made from an insulative material. The probe body <b>204</b> and the probe tip <b>202</b> are configured to be coupled to a test lead (not shown). The test lead is configured to be coupled to an input/output of a test instrument (not shown).

The probe body <b>204</b> includes a handle portion <b>206</b> and a top portion <b>208</b>. The handle portion <b>206</b> may be coupled to the test lead. The top portion <b>208</b> may include a nose <b>210</b>, a finger guard <b>212</b>, and a collar <b>214</b> or any combination thereof. The collar <b>214</b> of the top portion <b>208</b> is mechanically coupled to the handle portion <b>206</b> of the probe body <b>204</b>. This coupling may be a press fit, snap fit, threaded coupling or any other mechanical coupling now known or later developed. An insulative sleeve <b>216</b> is positioned within the probe body <b>204</b> and extends from the nose <b>210</b> of the top portion <b>208</b>. However, if the top portion <b>208</b> only includes a collar <b>214</b>, the insulative sleeve would extend directly from the collar <b>214</b>. The insulative sleeve <b>216</b> is made from an insulative material. The probe tip <b>202</b> extends from the insulative sleeve <b>216</b>. In some embodiments, the probe tip <b>202</b> remains stationary within the probe body <b>204</b>. However, the insulative sleeve <b>216</b> is extendable and retractable from the probe body <b>204</b>.

In <figref idrefs="DRAWINGS">FIG. 2A</figref> the insulative sleeve <b>216</b> is retracted into the top portion <b>208</b> of the probe body <b>204</b>. In <figref idrefs="DRAWINGS">FIG. 2B</figref> the insulative sleeve <b>216</b> extends from the top portion <b>208</b> of the probe body <b>204</b> so that the insulative sleeve <b>216</b> surrounds a portion of the probe tip <b>202</b>. As can be seen from <figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref>, when the insulative sleeve <b>216</b> is retracted into the top portion <b>208</b> of the probe body <b>204</b>, more of the probe tip <b>202</b> is exposed then when the insulative sleeve <b>216</b> is extending from the top portion <b>208</b> of the probe body <b>204</b>.

The insulative sleeve <b>216</b> extends and retracts from the nose <b>210</b> of the top portion <b>208</b> when the top portion <b>208</b> of the probe body <b>204</b> is rotated relative to the handle portion <b>206</b>. By rotating the top portion <b>208</b> in a first direction the insulative sleeve <b>216</b> extends from the top portion <b>208</b>. Conversely, by rotating the top portion <b>208</b> in a second direction, such as a direction opposite the first direction, the insulative sleeve <b>216</b> retracts into the probe body <b>204</b>. Additionally, and in the embodiment shown in <figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref>, the collar <b>214</b> of the top portion <b>208</b> of the probe body <b>204</b> may include an opening <b>220</b>. The opening <b>220</b> may be aligned with a label <b>221</b> to communicate the length of the exposed probe tip <b>202</b> or the category rating that the length of the probe tip <b>202</b> is qualified for under the safety standards discussed above. For instance, the label <b>221</b> may be aligned with a first label when the insulative sleeve <b>216</b> is fully retracted into the probe body <b>204</b> as is shown in <figref idrefs="DRAWINGS">FIG. 2A</figref> and aligned with a second label when the insulative sleeve <b>216</b> is fully extended from the probe body <b>204</b> as is shown in <figref idrefs="DRAWINGS">FIG. 2B</figref>. Thus the label <b>221</b> communicates to a user the length of the probe tip <b>202</b> exposed from the insulative sleeve <b>216</b>. This label <b>221</b> may be a visual element or a physical element. The label <b>221</b> may indicate the category rating the length is rated for or the actual length of the exposed probe tip <b>202</b>.

<figref idrefs="DRAWINGS">FIGS. 3A and 3B</figref> are cross sectional schematic drawings of a test probe <b>300</b> comprising a test probe tip <b>202</b>, an insulative sleeve <b>216</b>, a top portion <b>208</b>, and a handle portion <b>206</b> of a probe body according to one embodiment of the invention. The top portion <b>208</b> of the probe body includes a nose <b>210</b>, a finger guard <b>212</b>, and a collar <b>214</b> as described in reference to <figref idrefs="DRAWINGS">FIGS. 2A and 2B</figref>. In this embodiment, an inner surface of the top portion <b>208</b> includes two protrusions or pins <b>222</b> and <b>224</b>. The insulative sleeve includes two helices <b>226</b> and <b>228</b>, which in the embodiment shown are cut outs along the surface of the insulative sleeve <b>216</b>. The protrusions <b>222</b> and <b>224</b> on the inner surface of the top portion <b>208</b> are positioned so that as the top portion <b>208</b> is rotated in a first direction, the protrusions <b>222</b> and <b>224</b> guide the movement of the insulative sleeve <b>216</b> by moving along the respective helices <b>226</b> and <b>228</b>, thus, causing the insulative sleeve <b>216</b> to extend from the top portion <b>208</b> of the probe as is shown in the test probe <b>300</b> in <figref idrefs="DRAWINGS">FIG. 3A</figref>. As the top portion <b>208</b> of the probe is rotated again, the pins <b>222</b> and <b>224</b> guide the movement of the insulative sleeve <b>216</b> causing the insulative sleeve <b>216</b> to retract into the top portion <b>208</b> of the probe as is shown in <figref idrefs="DRAWINGS">FIG. 3B</figref>. The embodiment in <figref idrefs="DRAWINGS">FIGS. 3A and 3B</figref> show the top portion having two pins. However, as will be clear to a person of ordinary skill in the art the top portion may have only one pin or more than two pins to guide the movement of the insulative sleeve. In one embodiment, if the top portion has one pin, then the insulative sleeve may have one helix. In one embodiment, the top portion <b>208</b> may be rotated in the same direction to extend and retract the probe tip <b>202</b>. In another embodiment, the top portion <b>208</b> may be rotated in a first direction to extend the probe tip <b>202</b> and rotated in the opposite direction to retract the probe tip <b>202</b>.

<figref idrefs="DRAWINGS">FIG. 4A</figref> is an isometric schematic drawing of an insulative sleeve <b>217</b> according to one embodiment of the invention. The insulative sleeve <b>217</b> is designed to be used with a single pin. The insulative sleeve <b>217</b> includes a helix <b>226</b> having a main section <b>230</b>, a first end <b>232</b>, and a second end <b>234</b>. The first end <b>232</b> of the helix <b>226</b> has a first detent or first lock position <b>236</b> and the second end <b>234</b> of the helix <b>226</b> has a second detent or second lock position <b>238</b>. When a pin is positioned in either the first or second detent <b>236</b> and <b>238</b>, the pin is moved out of the main section <b>230</b> of the helix <b>226</b>. More particularly, when the pin is positioned in either the first or second detent <b>236</b> and <b>238</b>, the insulative sleeve <b>217</b> is latched into position relative to the probe. <figref idrefs="DRAWINGS">FIG. 4B</figref> is an isometric schematic drawing of an insulative sleeve <b>216</b> according to another embodiment of the invention. The insulative sleeve <b>216</b> includes two helices <b>226</b> and <b>228</b>. Each helix <b>226</b> and <b>228</b> has a main section <b>230</b>, a first end <b>232</b> of the helix, a second end <b>234</b> of the helix, a first detent <b>236</b> and a second detent <b>238</b>.

Moving the insulative sleeve <b>216</b> from a first position <b>217</b> to a second position <b>219</b> will now be explained in reference to <figref idrefs="DRAWINGS">FIGS. 3A</figref>, <b>3</b>B, and <b>4</b>B. In <figref idrefs="DRAWINGS">FIG. 3A</figref>, the pins <b>222</b> and <b>224</b> are latched in a respective second detent <b>238</b>. When the pins <b>222</b> and <b>224</b> are latched in the second detent <b>238</b>, the insulative sleeve <b>216</b> is fully extended and insulates a portion of the probe tip <b>202</b> that extends from the top portion <b>208</b> of the probe body. Thus, the exposed length of the probe tip <b>202</b> is the length that extends from the insulative sleeve <b>216</b>. To cause the insulative sleeve <b>216</b> to retract into the top portion <b>208</b> of the probe body, a rotational force may be applied to the top portion <b>208</b> to cause the pins <b>222</b> and <b>224</b> to enter a respective second end <b>234</b> of the helices <b>226</b> and <b>228</b>. Once the pins <b>222</b> and <b>224</b> are positioned within the second end <b>234</b> of the helices <b>226</b> and <b>228</b>, the top portion <b>208</b> of the probe body may be further rotated to cause the pins <b>222</b> and <b>224</b> to guide the insulative sleeve <b>216</b> to move along the main section <b>230</b> of the helices <b>226</b> and <b>228</b>. As the pins <b>222</b> and <b>224</b> move along the main section <b>230</b> of the respective helices <b>226</b> and <b>228</b> from the second end <b>238</b> to the first end <b>232</b>, the insulative sleeve <b>216</b> retracts into the top portion <b>208</b> of the probe body. The pins <b>222</b> and <b>224</b> move along the respective main section <b>230</b> of the helices <b>226</b> and <b>228</b> until the pins <b>222</b> and <b>224</b> reach the first end <b>232</b> of the helices <b>226</b> and <b>228</b>. At the first end <b>232</b> of the helices <b>226</b> and <b>228</b>, as the top portion <b>208</b> is further rotated, the pins <b>222</b> and <b>224</b> are positioned in the first detent <b>236</b>. When the pins are positioned in the first detent, the insulative sleeve is fully retracted into the probe.

The rotation force required to move the pins <b>222</b> and <b>224</b> from the first detent to the first end of the helix is generally greater than the rotation force required to move the pin along the main section of the helix. Similarly, the rotational force required to move the pin from the second detent to the second end of the helix is generally greater than the rotation force required to move the pin along the main section of the helix. Therefore, when the pin is positioned in either the first detent or the second detent, the insulative sleeve is latched into a respective position.

<figref idrefs="DRAWINGS">FIG. 5A</figref> is an isometric schematic drawing of the top portion <b>208</b> shown in <figref idrefs="DRAWINGS">FIGS. 3A and 3B</figref>. <figref idrefs="DRAWINGS">FIG. 5B</figref> is cross sectional schematic drawing of the top portion in <figref idrefs="DRAWINGS">FIG. 5A</figref>. <figref idrefs="DRAWINGS">FIG. 5C</figref> is an schematic drawing of the top portion in <figref idrefs="DRAWINGS">FIG. 5A</figref>. In this embodiment and as is most clearly shown in <figref idrefs="DRAWINGS">FIGS. 5B and 5C</figref>, the top portion <b>208</b> includes two pins <b>222</b> and <b>224</b>. As discussed above, the two pins <b>222</b> and <b>224</b> are configured to be positioned so that they are aligned with the helices <b>226</b> and <b>228</b> on the insulative sleeve <b>216</b>. Additionally, the top portion <b>208</b> further includes an opening <b>220</b> to be aligned with a label. The label communicates the length of the exposed probe tip <b>202</b> or the category rating that the length of the probe tip <b>202</b> is qualified for under the safety standards discussed above. For instance, in one embodiment when the insulative sleeve <b>216</b> is fully extending from the nose <b>210</b> so that the pins <b>222</b> and <b>224</b> are positioned in the first detents <b>236</b>, a first label may be aligned with the opening <b>220</b>. Conversely, when the insulative sleeve <b>216</b> is retracted into the nose <b>210</b> so that the pins <b>222</b> and <b>224</b> are positioned in the second detents <b>238</b>, a second label may be aligned with the opening <b>220</b>. The first and second labels may be positioned on any appropriate device that is operable to be aligned with the opening <b>220</b>. In one embodiment, the labels are positioned on a portion of the probe body <b>204</b>. In another embodiment, the labels are positioned on a portion of the insulative sleeve <b>216</b>. As stated above, each label indicates to a user which category rating the length of the exposed part of the probe tip is rated for.

Although the present invention has been described with reference to the disclosed embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For instance, the insulative sleeve may be indexable to a plurality of positions. The insulative sleeve may have a first and second detent coupled together by a first main helix as described above, but also a third detent coupled to the second detent by a second main helix. Therefore, the insulative sleeve would be able to latch into a third position, when the pin is positioned in the third detent. This third position would result in a third length of the probe tip extending from the top portion of the probe body. Additionally, the insulative sleeve may extend to a third position in which the insulative sleeve completely covers the probe tip. Furthermore, any means of communication may be used to communicate to a user that the probe tip or the insulative sleeve has been indexed, such as a visual element, an audio element, or a raised surface on the label portion that a user can feel to determine the length of the exposed probe tip or the category rating. Any method of latching the insulative sleeve into a particular position may be used. Such modifications are well within the skill of those ordinarily skilled in the art. Accordingly, the invention is not limited except as by the appended claims.